Refrigerating system



March 29, 1938.

c. A. OTTO 2,112,344

REFRIGERATING SYSTEM Filed Aug. 9, 1955 RETURN AIR,

Patented Mar. 29,193

nan-"momma srs'rm Carl A. Otto, Milwaukee, Wis, mimito Johnson Service Company, Mllwank ee, Win, a corporation of Wisconsin Application August a, 1935. Serial No. 35,539

16 Claims.

This invention relates to refrigeration andparticularly to air conditioning under summer conditions by theme of direct expansion coolers forming part of a refrigerating circuit.

The features of novelty reside chiefly in an automatic expansion valve having a primary control and a secondary or modifying control.

The primary control is eflected by evaporator pressure and evaporator temperature in the usual manner. The secondary control is in response to the combined effects of temperature in the condi-' tioned space and out of door temperature, and specifically to the differential between these temperatures. Means are provided to adjust the relation in which the two temperatures are combined to produce the modifying effect.

The outdoor temperature may be dry bulb temperature, wet bulb temperature, effective temperature (a combination of wet bulb and dry bulb temperatures) or temperature developed by radiation. Thermostatic elements which respond to each of these temperatures are known and their construction is not a feature of the present invention.

A simple embodiment of the invention will now be described with reference to the accompanying drawin i .Whi h.

Fig. 1 is a diagram of the conditioning circuit.

Fig. 2 is an axial section through the expansion valve.

Fig. 3 is a fragmentary section showing a modification.

Fig. 4 shows a wet bulb thermostatic unit.

Fig. 5 shows an effective temperature thermostatic unit.

Fig. 6 shows a thermostatic radiation.

Referring first to Fig. 2, the body of the expansion valve is indicated at ii and its cap at l2. Sealed in the joint between them is the outer periphery of a bellows diaphragm l3 which serves both as a packless gland and as a motor abutment on which evaporator pressure acts upward.

The liquid line is connected at M and leads to a downwardly facing expansion valve seat l5 formed as a removable bushing. With seat l5 a needle. valve i5 coacts, the valve being adjustably threadunit responsive to ed in a yoke il attached to the center of bellows diaphragm i5, as shown. Valve i6 is urged in a closing direction by a coil compression spring i5 seated in closure plug i9 which is threaded in body ii. Removal of the plug permits access to the 'valve for adjustment thereof.

Expanded refrigerant is led from housing ll through connection 2| which is forward of the plane of section of Fig. 2, .but is visible in Fig. 1, so that diaphragm I2 is subject to the pressure of expanded refrigerant acting upward.

A vertically slidable plunger 22 is in one-way thrust engagement with the upper side of die: 5 phragm l3 and is slotted at 22 and formed with a knife edge 24 to react with a lever 25 which is pivoted at 26 in housing 21 carried by cap l2 and extends through the slot.

Plunger 22 carries at its upper end a flange 28 against which a coil compression spring 29 acts in an upward direction. Spring 29 reacts against shell 5i which encloses a bellows diaphragm 32. Bellows diaphragm 22 is sealed at its outer margin to shell 3i and at its inner margin to flange 28, as indicated. Shell ii is vertically adjustable by turning sleeve 33 which is swiveled to the shell at 34 and threaded to neck 35 on housing 21. A tube 35 transmits to the-interior of shell 3 l above bellows 32, the pressure developed in thermostatic bulb 31 (see Fig. 1).

The mechanism so far described will be recognized as embodying the essential features of commercial automatic expansion valves, plus the lever through which the modifying control forming 25 a feature of the present invention is applied.

Mounted on housing 21 is a sheli 38 to which is sealed a pressure motor comprising a movable head 39 loosely guided on boss I and metal bellows 42, sealed at one end to head 39 and at the other to shell 38. A link 43 is rigidly connected to head 39 and is pivoted to lever 25 at 44. A coil compression spring 45 urges head 39 upward and thus causes lever 25 to exert a valve closing force.

A connection admits against the upper side of head 39, the pressure developed in branch line 41 by a pneumatic thermostat 58, of any suitable type, conveniently that shown in the patent to Otto No, 1,500,260, July 8,1924, and subject to temperature in the cooled space, Consequently on rising temperature in the cooled space, the closing tendency developed by the spring is partly or wholly neutralized but no valve opening tendency is created because of the clearance below lever 25 in the slot 22.

The structure so far described is essentially that described and claimed in my allowed application Serial No. 742,495,'filed September 1, 1934, which has issued as Patent 2,019,724, on November 5, 1935.

A shell 5| encloses a bellows diaphragm 52, which is sealed on its outer margin to shell 5| and at. its inner margin to head 52. Head 53 is guided on boss 54 and is connected to push rod 55 whose bifurcated end straddles a lever 56 pivoted at 51 to housing 21. 'The push rod is guided at 58 and has a knife edge 59 which engages lever 56. A block 6| forms a thrust connection between lever -56 and lever 25, and is shiitable to vary the leverage ratio by means of a screw 52 which is swiveled in lugs 63 on lever 55 and is threaded in the block 5|. A knurled head 64 is provided to turn the screw.

The bellows diaphragm 52 is subject in an upward direction to pressure developed in tube 65 by thermostatic bulb 65, and thus assists spring 45.

Y Referring now to Fig. 1. The space to be conditioned is represented by 51 and the conditioner housing by 68. A fresh air inlet to housing 61 is controlled by louvers 69 while a recirculation duct 'il delivers air from space 61 to the conditioner. I

The cooling evaporator is shown at .12 and the total volume fan at 13. Washing sprays and similar familiar details are omitted to simplify the drawing but may be used.

The thermostatic bulb 31 is shown clamped to the suction line 14 leading from the evaporator 12. Valve l5 controls the supply of refrigerant from the liquid line 15 to evaporator 12. Bulb 66 is located out of doors. 7

Bulb 66 may respond to dry bulb temperature, but in some cases it is preferable to cause it to respond to wet bulb temperature in which case it may be given a wet envelope I6 as indicated in Fig. 4. It may be caused to respond to what is called effective temperature by giving it a partial wet envelope 11 as indicated in Fig. 5. It may be made to respond to radiation by enclosing it in a copper globe 18 having a dull black surface, as indicated in Fig. 6.

In any case the arrangement is such that the primary control efiected by evaporator pressure and suction temperature (superheat control) is modified by the diiferential between indoor temperature and some outdoor temperature (wet bulb, dry bulb, effective, radiation etc.) The established differential may be varied by shifting block GI and thus varying the control relation between the indoor and outdoor temperature.

Instead of using a pneumatic thermostat 48 a thermostatic bulb and related bellows motor may be substituted as indicated in Fig. 3. Here the unit 38a replaces thestructure in casing 38 I and bulb 48a replaces pneumatic thermostat 48, the two'being connected by tube "a. The mechanical construction of unit 38a is essentially the same as that of parts 28 to 35 inclusive and need not be again described indetail.

In the various arrangements suggested, regulation effected in response to room temperature is modified in response to some out-door temperature condition, and the action is directly upon the expansion valve, thus securing immediate response and emcient operating conditions over a wide load range.

Various modificationsare possible within the scope of the invention and are contemplated. The embodiments specifically described are intended to be illustrative.

What is claimed is, a

1. The method of regulating an expansion valve to control a space-cooling evaporator which comprises varying the opening of said valve in response to the resultant of four forces, namely, a closing force proportional to evaporator pressure, an opening force which increases with I evaporator discharge temperature; a closing force which increases as space temperature falls, and a closing force which increases as temperature external to the space rises, the last-named temperature being such as to affect heat leakage to the space.

2. The method 'of regulating an expansion valve to control a space-cooling evaporator, which comprises varying the opening of said valve in response to the resultant of a closing force proportional to evaporator pressure, and

I an opening force which increases with evaporator ment subject to evaporator pressure and urging said valve in a closing direction; a thermostat subject to the temperature of evaporator dis charge; means controlled by said thermostat serving to exert on said valve an opening force which increases with rising temperature; two thermostats, one subject to the temperature of the medium cooled by the evaporator and the other subject to an external temperature tending to cause heatleakage to said medium; and means controlled by the last-named two thermostats conjointly and serving to exert a resultant closing force on said valve, said force being increased as temperature of'the medium falls and as said external temperature rises.

4. In a cooling device, the combination of an evaporator; a valve controlling the supply of volatile refrigerant thereto; a movable abutment subject to evaporator pressure and urging said valve in a closing direction; a thermostat subject to the temperature of evaporator discharge; means controlled by said thermostat serving to exert on said valve an opening, force which increases with rising temperature; two thermostats, one subject to the temperature of the medium cooled by the evaporator. and the other subject to an external temperature tending to cause heat leakage to said medium; means controlled by the last-named two thermostats conjointly and serving to exert a resultant closing force on said valve, said force being increased as temperature of the medium falls and as said external temperature rises; and adjustable loading means biasing said valve in a closing direction.

5. In a cooling device, the combination of an evaporator; a valve controlling the supply of volatile refrigerant thereto; a movable abutment subject to evaporator pressure and urging said valve in a closing direction; a thermostat subject to the temperature of evaporator discharge; means controlled by said thermostat serving to exert on said valve an opening force which increases with rising temperature; two thermostats, one subject to the temperature of the medium cooled by the evaporator and the other subject to an external temperature tending to cause heat leakage to said medium; means controlled by the last-named two thermostats conjointly and serving to exert a resultant closing force on said valve, said force being increased as temperature of the medium falls and as said external temperature rises; and means for adjusting the relative effects of the last-named two thermostats on the means controlled thereby.

6. In a cooling device, the combination of an evaporator; a valve controlling the supply of volatile refrigerant thereto; a movable abutment subject to evaporator pressure and urging said valve in a closing direction; a thermostat subject to the temperature of evaporator discharge; means controlled by said thermostat serving to exert on said valve an opening force which increases with rising temperature; two thermostats, one subject to the temperature of the medium cooled by the evaporator and the other subject to an external temperature tending to cause heat leakage to said medium; means controlled by the last-named two thermostats conjointly and serving to exert a resultant closing force on said valve, said force being increased as temperature of the medium falls and as said external temperature rises; and means comprising a lever ratio changing device for modifying the effect of the thermostat subject to said external temperature.

7. In an expansion valve, the combination of a valve; a movable abutment subject to pressure on the discharge side of the valve and urging the valve in a. closing direction; and three thermostatically responsive motors, responsive to different temperatures, two of which oppose the third, and all of which are operatively related with said valve to control the movements thereof.

8. In an expansion valve, the combination of a valve; a movable abutment subject to pressure on the discharge side of the valve and urging the valve in a closing direction; three thermostatically responsive motors, responsive to different temperatures, two of which oppose the third, and all of which are operatively related with said valve to control the movements thereof; and leverage changing means affecting the relation of one of said motors to the others.

9. In an expansion valve, the combination of a valve; a movable abutment subject to pressure on the discharge side of the valve and urging the valve in a closingdirection; three thermostatically responsive motors, responsive to different temperatures, two of which oppose the third, and all of which are operatively related with said valve to control the movements thereof; and adjustable means for biasing said valve in a closing direction.

10. In an expansion valve, the combination of a valve; a movable abutment subject to pressure on the discharge side of said valve and urging said valve in a closing direction; a movable memher in one-way thrust relation with 'said valve,

and shiftable to urge the valve in an opening direction; and three thermostatically responsive motors, responsive to different temperatures, and arranged to control the shifting of said movable member.

11. In an expansion valve, the combinatiomof a valve; a movable abutment subject to pressure on the discharge side of said valve and urging,

said valve ina closing direction; a movable member in one-way thrust relation with said valve, and shiftable to urge the valve in an opening direction; three thermostatically responsive motors, responsive to different temperatures, and arranged to control the shifting of said movable member; and leverage changing means for mod-' ifying the effect of at least one of said motors.

12. In a cooling device, the combination of an evaporator; an expansion valve controlling the supply of volatile refrigerant thereto, said expansion valve comprising means responsive to evaporator pressure tending to close the valve and means responsive to temperature of the refrigerant at the discharge of the evaporator tending to open the valve in response to rising refrigerant temperature; and means responsive to the differential between the temperature of the medium cooled by the evaporator, and the temperature of a medium tending to cause heat leakage to the first named medium, said'means exercising a modifying control on said valve.

13. The method of regulating an expansion valve to control a space cooling evaporator, which comprises limiting the opening movement of the valve in responseto superheat of refrigerant leaving the evaporator and moving the valve in a closing direction from the point so limited in proportion to a variable unidirectional force, and causing said force to vary inversely with respect to space temperature and directly with respect to a temperature external to the space.

14. The method of regulating an expansion valve to control a space cooling evaporator, the

temperature in the space so cooled being subject a to increase by the intensification of a condition external to said space, which comprises limiting the opening of said valve in response to the superheat of refrigerant leaving said evaporator, and

subjecting said valve to a unidirectional closing subject to the temperature of the room cooledby the evaporator and. serving to develop a valve closing force which force increases as space temperature falls, and the other thermostat being subject to a temperature external to the cooled space and serving to develop a valve closing force which increases as said external temperature rises.

16. In a cooling device, the combination of an evaporator; a valve controlling the supply of volatile refrigerant thereto; thermostatic means responsive to superheat of refrigerant leaving said evaporator and serving to determine the maximum opening of said valve; two thermostats arranged conjointly to urge said valve in a closing direction only, one of said thermostats being subject to the temperature of the room cooled by the evaporator and serving to develop a valve closing force, which force increases as space temperature falls, and the, other thermostat being subject to a temperature external to the cooled space and serving to develop a valve closing force which increases as said external temperature rises; and force ratio changing means for varying the efiect of at least one of said thermostats.

CARL A. OTTO. 

